Learn all about common fly species from egg to adult, often found in poultry houses with manure and explore various methods to control them.

The house fly prefers sunlight and is a very active fly.

Fly control is an integral part of poultry management. With today’s concern about environmental conditions, fly control takes on added importance. Besides their ability to mechanically carry disease organisms, flies may be considered environmental pollutants just by their presence.

Several species of flies are common in and around laying houses. The most common are the house fly and little house fly.

The house fly breeds in moist, decaying plant material including refuse, spoiled grains and feeds, and in all kinds of manure. Although it breeds in poultry manure, this is not a favorite medium. For this reason, it is more likely to be a problem around poultry houses where general sanitation is poor. The house fly prefers sunlight and is a very active fly that crawls about over filth, people, and food products with equal disdain. It is, therefore, the most important species from the standpoint of spreading human and poultry diseases and fly-specking eggs. This fly is also the intermediate host for the common tapeworm in chickens.

The little house fly is generally somewhat smaller than the house fly, but the size difference is not enough to be a good distinguishing characteristic. The little house fly prefers a less moist medium than the house fly in which to breed. Poultry manure is preferred over most other media. It prefers shade and cooler temperatures and is often seen circling aimlessly beneath hanging objects in the poultry house, egg room, and feed room. This fly is less likely to crawl about on people and food than is the house fly. On the other hand, it is usually the one that causes people living near poultry establishments to complain about a fly problem. Because of its preference for shade, it may collect in large numbers in nearby garages, breezeways, and homes. House flies and little house flies are capable of movement up to 20 miles from the site of development, but normally they move no more than a mile or so from this locality.

Blow flies (green or blue bottle flies) may occur in poultry houses. They breed in decaying animal carcasses including dead birds, dog manure, broken eggs, and wet garbage. Any reasonable sanitation program is usually sufficient to hold them in check.

Soldier flies are large (about twice the size of a house fly), blackish flies commonly found around poultry manure. They are not pests in that they use the manure only as breeding medium and do not bother anything else. They may even be considered beneficial since their larvae appear to render manure unsuitable for production of house fly larvae.

Fruit flies are sometimes produced in large numbers where there is a mixture of manure, wasted feed, and water. Nearby homes may become targets of these flies with resulting complaints to the poultryman. Elimination of large amounts of wasted feed and repair of leaking water systems usually solves this problem.

Biology of Flies

All flies go through four life stages. These are the egg, larva, pupa, and adult fly. Eggs are deposited on the breeding media, and larvae or maggots develop in this moist or wet material until ready to pupate. Generally, the mature maggots crawl out of this material and seek a drier place to pupate. Here they form a brown seed-like puparium from which the adult fly emerges. This development from egg to adult fly can take place in as little as seven to ten days under ideal conditions.

Cultural-Biological Control

Management of manure in such a way that it is not attractive for fly breeding is the most effective means of fly control. Fresh poultry manure generally contains 60 to 80 percent moisture. Fly breeding in this material can be virtually eliminated by reducing its moisture content to 30 percent or less or by addition of moisture to liquify it. Drying usually is preferable since dry manure is more easily handled, occupies less space, and has less associated odor problems than does liquid manure.

Chemical Control of Flies

Insecticides should be considered as supplementary to sanitation and management measures aimed at preventing fly breeding. A number of insecticides are available under various trade names for use as:

• residual sprays
• space sprays, mists, and fogs
• resin strips
• baits
• larvicides

Often, the same insecticide can be used in more than one of these control methods. Talk to your feed dealer about recommended materials for poultry houses. Follow directions carefully. Approved materials will not result in egg or meat contamination or injure birds if directions for use are strictly followed.

Residual sprays are usually the most effective and economical for controlling potentially heavy populations of adult flies of any species present. Such sprays should be applied in the spring at the beginning of the fly season. As a rule, they will continue to kill flies up to eight weeks. It is important that such insecticides be applied to surfaces on which flies alight. Generally, the framework of the house, the ceiling, trusses, wires that support cages, electric light wires and fixtures, etc. are favorite gathering places for the house fly and the little house fly. The outside of the poultry house, particularly around openings plus any shrubs or weeds adjacent to the house should also be sprayed since blow flies tend to congregate here. Do not spray birds or contaminate feed or water.

Space sprays, mists, and fogs with quick knockdown but no residual action are advantageous where immediate reduction of an adult fly population is necessary. There are many machines on the market designed to produce the small spray particle size desired for this type of application. Space applications should be to the point of “filling” the room with mist or fog.

Resin strips containing 20 percent dichlorvos (DDVP, Vapona) are readily available. When used according to directions, they give off a vapor that kills flies in enclosed areas where there is little or no air circulation. Thus, they are most effective in places such as feed rooms and egg rooms adjacent to the main poultry house. They are not effective in poultry houses because of the greater air circulation. Use one strip for each 1,000 cubic feet of room space.

Baits may be used in either a liquid or dry form. They usually contain an insecticide plus sugar or some other attractant. Baits are most useful as a supplement to residual sprays. They alone cannot be expected to control fly populations. Commercial dry baits in granular form are readily available, but liquid baits will have to be prepared by the user. Liquid baits are usually more effective since they can be brushed upon a wide variety of fly resting surfaces, as well as being placed in flat containers usually used for dry baits. Liquid baits should be used as soon as mixed and not stored for later use. They have the disadvantage of collecting dirt and dust. All baits must be placed out of reach of the birds.

Larvicides are applied directly to the manure below cages, screen wire, or slats. This type of application is designed to kill fly larvae (maggots) developing in the manure. It is necessary that the insecticide penetrate the manure and contact the maggots to kill them. This is often difficult since the constant addition of fresh manure offers new breeding material free of insecticide. This type of application is best utilized when reserved for treatment of fly breeding spots not eliminated by normal cultural practices.

Excerpted with permission from The Backyard Chicken Book: A Beginner’s Guide by H. Lee Schwanz. Copyright 2014 by Skyhorse Publishing, Inc.